This app can check whether 5G is Sub-6, mmWave, LTE frequency 5G, or anchor band. In addition, if you are connected to 5G, you can also check whether you are using standalone (5G SA) or non-standalone (5G NSA). If you are using 5G but it switches to 4G after communication, it is likely that you are using the anchor band. There is a widget function, so you can check it from the home screen. There is also a function that allows you to check the notification icon even in the background. This app is open source. You can check the source code here. https://github.com/takusan23/NewRadioSupporter